Bicycles with lever action drive usually have a fixed drive ratio. Some have been made with adjustment means for changing the ratio, such as by moving the drive chain or cable attachment to the pedal lever, which requires stopping the pedal action to make the adjustment. My U.S. Pat. No. 3,913,945 incorporates such a mechanism but requires only a slight hesitation in the pedal action to change the ratio.
Using a conventional multi-ratio gear assembly on the drive wheel axle would not be practical, since the pedal levers are usually independently operated and two such bulky hubs would be required.